The present invention relates generally to the formation of integrated circuit devices and structures, and more specifically to a technique for filling plugs through chemical mechanical polishing.
Silver and other malleable metals including gold, platinum, and copper are considered important materials for manufacturing a variety of integrated circuits such as memory devices. For example, aluminum is a commonly used metal for forming devices and interconnects.
Unfortunately, there are a number of manufacturing obstacles attributable to the use of such materials in integrated circuit device fabrication. For example, one common processing technique, chemical mechanical polishing (CMP), is commonly employed in integrated circuit device fabrication for polishing away conductive materials for forming plugs, interconnects and other devices. However, it is not uncommon for certain malleable metals such as silver and silver-based materials to inadvertently pull from the plug during CMP processing. This is particularly problematic when forming devices and interconnects where silver is intended to form a plug coupling to an underlying layer of tungsten. Silver adheres poorly to tungsten, thus the silver pulls easily from the plug. Even in cases where the metal does not completely pull from the via, inconsistent or otherwise unreliable structures such as partially filled vias can result post CMP. This can lead to open circuit connections or high resistance plugs.
Therefore, there is a continuing need for a CMP process in integrated circuit device fabrication that allows consistent and reliable formation of devices and interconnects using malleable metals.